This invention relates to a vapor recovery fuel dispensing nozzle of the balanced-type, for example, as disclosed in U.S. Pat. No. 5,255,723 ('723 patent) which issued to the assignee of the present invention and the disclosure of which is herein incorporated by reference. Other forms of vapor recovery fuel dispensing nozzles of the balanced-type where fuel vapors are displaced from the vehicle fuel tank back into the underground tank, are disclosed in U.S. Pat. No. 4,697,624, No. 5,655,576, No. 6,951,229, and No. 7,082,972. In such a fuel dispensing nozzle assembly, a collapsible corrugated rubber bellows surrounds a fuel supply spout and defines therebetween a vapor return passage connected to a vapor return passage within the nozzle body and within a co-axial fuel supply hose. When a nozzle spout is inserted into a fuel fill tube or pipe projecting from a fuel tank of a motor vehicle, an annular vapor seal carried by the bellows engages the lip of the fill pipe. As the bellows is axially compressed by further pressure on the nozzle, a valve within the vapor passage opens. Axial compression of the bellows is also effective to actuate a diaphragm operated ball clutch which locks an axially movable stem to the nozzle body to form a fixed pivot support for a hand actuated lever connected to control a valve within the fuel supply passage.
When the annular resilient vapor seal engages the fuel fill pipe, it is desirable to obtain and maintain a positive and uniform annular pressure seal between the annular resilient vapor seal and the fill pipe to assure that fuel vapors displaced in the fuel tank transfer into the vapor return passage within the nozzle. It is also desirable to minimize the resistance to the flow of vapors into and through the fuel dispensing nozzle and into the vapor passage within the co-axial hose connecting the nozzle to the fuel dispenser since there is commonly no suction on the vapor return passage. It has been found that a collapsible bellows produces resistance to the vapor flow and sometimes does not produce a uniform pressure seal around the fuel tank fill pipe.